ISLAMORADA -- Workers for the contractor that runs the village's north Plantation Key sewer plant were cleaning up sewage Monday afternoon following an estimated 2,000- to 3,000-gallon spill early that morning.

"It was contained on the plant site," said Bob Dick, senior area manager for contractor Severn Trent. "Putting [sewage] on the ground is not ideal, but it didn't enter into any storm-drain system or waterway."

The spill is believed to have begun sometime after 3 a.m. Monday. It was discovered at 6:40 a.m., when the first worker arrived for his Monday shift. The plant was operational again by 10 a.m., Dick said.

He said the spill was probably caused by an electrical failure that was specific to the control panel for the floats of the main holding tank. Normally, the floats are suspended from a wire in the tank. When water gets high enough to make them float, they send a signal that tells a pump to begin pulling water from the holding tank into the disinfection area. However, when the power on the control panel failed Monday, the floats could not send the signal. Instead, water continued to rise into the holding tank, causing the spill.

Dick said the spill contained a combination of raw and partially treated sewage. An electrician was on the scene of the Mile Marker 89.8, bayside, plant before noon Monday. Severn Trent had already begun the process of cleaning the spill. Dick estimated that 90 to 95 percent of the material could be collected. After that, the ground was to be disinfected with hydrated lime.